U.S. Pat. No. 3,839,796 discloses the use of a hard base and teeth fixed thereto, together with a relatively soft deflectable and formable layer so that the teeth, the hard base and the deflectably formable layer may be inserted in a patient's mouth and wherein the deflectably formable layer may be deflected and form fitted to an edentulus ridge in the patient's mouth whereupon curable plastic material may subsequently be placed in the trough of the soft layer and reinserted in the patient's mouth for final impression fitting such that a hard liner is impression formed adjacent to the soft layer and the resultant denture is as disclosed in said U.S. Pat. No. 3,839,796.
It has however, been desirable to form a totally hard base structure which is impression formed relative to an edentulus ridge in a patient's mouth and various attempts have been made to strip the aforementioned deflectably formable layer from the hard base and cast a final hard impression formed liner against the hard base in dental stone molds. This has been accomplished. However, the stripping of the soft deflectable formable layer from the hard base preliminary to casting the final layer in dental stone molds has been difficult and, in many instances, the final casting of a curable hard plastic against the base material has resulted in the bonding of said last mentioned plastic to the surfaces of the plastic teeth which are in the dental stone molds and such has caused great difficulty in the cleaning of the final denture and the polishing thereof.